A biosupramolecular approach to graphene: Complementary nucleotide-nucleobase combinations as enhanced stabilizers towards aqueous-phase exfoliation and functional graphene-nucleotide hydrogels

The ability to use RNA/DNA nucleotides as colloidal stabilizers for graphene would be an important asset, as a close graphene-nucleotide association would facilitate access to hybrid systems where the rich covalent and supramolecular chemistry of these biomolecules could be exploited alongside graphene in a number of applications. Unfortunately, single RNA/DNA nucleotides are inefficient graphene dispersants. Here we propose and demonstrate a supramolecular strategy which overcomes this limitation, affording aqueous dispersions of high quality graphene flakes with much improved colloidal stability. A nucleotide is combined with its complementary nucleobase yielding stable hydrogen-bonded supramolecular entities that adsorb more strongly on the graphene surface than their individual components. Based on this approach, graphene-nucleotide hybrid hydrogels could be readily obtained, where the graphene flakes were intimately and uniformly intermixed with the nucleotide-based gel phase. Such hydrogels exhibited higher uptakes and/or slower release profiles of dyes and drugs (rhodamine B, methylene blue and tetracycline) than their graphene-free counterparts. Cell proliferation tests suggested the graphene materials obtained with nucleotide-nucleobase stabilizers to be biocompatible. The present results constitute a novel strategy in the processing and molecular integration of graphene that could be extended to other (bio)molecules of interest towards the realization of functional materials for different applications.Financial support from both the Spanish Ministerio de Economía y Competitividad (MINECO) and the European Regional Development Fund (project MAT2015-69844-R) is gratefully acknowledged. Partial funding by Plan de Ciencia, Tecnología e Innovación (PCTI) 2013–2017 del Principado de Asturias and the ERDF (project GRUPIN14-056) is acknowledged as well. B.C. and O.P-V. are grateful to the European Social Fund for funding their contracts. A.P. is thankful for her research contract partially supported (80%) by the ERDF/FEDER Operative Programme of Región de Murcia (project no. 14-20-01).Peer reviewe